INSECTS 193 



Insects which are very numerous one season may be scarcely 

 noticed the following season. It is probable that at the end 

 of the first season 'most of them were attacked and killed by 

 parasites. Consequently but few were left to start new 

 generations the second year. 



Birds. Birds have been called " the farmer's friends," 

 because they greatly aid him in destroying insects that injure 

 his crops. The importance of attracting birds to the farm 

 and encouraging them to live there is so great that the follow- 

 ing chapter will be devoted to this subject. 



Mammals. The mole and skunk are common mammals 

 that are useful in destroying insects, although at times they 

 may become undesirable. The mole feeds upon worms, insect 

 larvae such as wireworms and white grubs, and insects that 

 live in the ground. The skunk eats a great variety of insects 

 such as grasshoppers, crickets, white grubs, tobacco and 

 tomato worms, and potato beetles. It also feeds upon field 

 mice and other small rodents. 



Learning more about insects. Nothing can take the 

 place of actually knowing insects, not from books, but by 

 watching what they do, how they grow, where they live, 

 when and where they lay their eggs and transform into the 

 different stages of their development. 



Such knowledge should grow by continued observation 

 from year to year, with such assistance as may be obtained 

 from bulletins and circulars, from state agricultural experi- 

 ment stations and the U. S. Department of Agriculture, 

 and from some good reference books on injurious insects. 



